The invention relates to a machine for polishing and planing substrates comprising:
at least one rotary polishing plate on which a substrate is polished,
a polishing head mobile in translation between a raised position and a lowered position and provided with a bearing element for support of the substrate,
a pivoting polishing arm designed to move the polishing head to pick up the substrate to be polished from the loading pallet and to convey it onto an unloading pallet after polishing,
at least one mechanism for driving the polishing plate and the bearing element of the polishing head in rotation, and for alternate movement of the polishing arm and of the loading and unloading pallets,
and a controller for control of the mechanism during the polishing cycle.
The document EP-A 774,323 describe a polishing machine of the kind mentioned making use of a carrousel mechanism to move the substrates onto a polishing table having a predetermined number of stations. The mechanism is located in the working zone and above the polishing table. This results in risks of pollution of the substrates in the course of polishing. Production has to be totally shut down when maintenance or tool-changing operations are performed on a given station. A carrousel machine of this kind is not extensible.
The document JP 63,207,559 describes a modular machine for grinding substrates, which are placed in cassettes and extracted by means of a loading unit which sends them to two grinding units by means of a transfer unit. After grinding, the substrate is mounted on a table of a washing unit and is stored after cleaning in cassettes of an unloading unit.
The document U.S. Pat. No. 4,680,893 refers to a machine for polishing semi-conductor substrates, having a conventional non-modular structure, equipped with a pivoting polishing arm with angular movement between a loading station, a cleaning station, a first polishing station, a second polishing station, and an unloading station.
A first object of the invention is to achieve a modular polishing machine, providing easy access to the working zone in complete safety.
A second object of the invention is to provide a multi-station polishing machine of modifiable configuration, using the largest possible number of standard elements.
The polishing machine according to the invention is characterized in that the machine comprises:
at least one base unit in the form of a parallelepipedic cubicle having a first loading and unloading surface, a second opposite parallel surface for access to the working zone situated in the intermediate compartment, and third and fourth surfaces comprising solid transverse walls extending perpendicularly to the first and second surfaces,
the loading pallet and unloading pallet are supported respectively by a loading arm and an unloading arm with operations independent from one another, said pallets both being accessible on the side where the first surface is situated,
the mechanism is situated in the bottom compartment underneath the intermediate compartment of the cubicle, whereas the controller of the base unit is located in the upper compartment, the mechanism being accessible on the side where the second surface is situated.
According to one feature of the invention, the polishing arm and the unloading arm are pivotally mounted around a first vertical axis. The base unit comprises a rotary conditioning head supported by a conditioning arm, which is pivotally mounted with the loading arm around a second vertical axis parallel to the first axis.
According to a preferred embodiment, a cleaning station is arranged between the two vertical axes, and between the polishing plate and the first surface of the cubicle so as to define a cleaning position of the polishing head and concentric positions of the loading and unloading pallets, and of the polishing head when substrate handling operations are performed. The mechanism comprises a geared motor housed in the bottom compartment and coupled to a rotary shaft extending in the direction of the first axis, said shaft driving a pulley and a belt-driven transmission housed in the polishing arm to move the polishing head in rotation. The rotary shaft extends inside a tubular column securedly united to the polishing arm and to an operating rod, which is controlled by a first jack to perform pivoting of the polishing arm between the cleaning station and the polishing plate. The unloading arm is securedly united to a sleeve mounted coaxially around the column with a tubular sheath interposed between the two, bearings being arranged between the sleeve and the sheath to allow a rotary movement of the unloading arm with respect to the polishing arm. An operating lever controlled by a second jack is securedly united to the sleeve to bring about the angular movement of the unloading arm.
A similar mechanism is used to actuate the conditioning and loading arm.
The complete machine, configured to the user""s requirements, can present very different structures:
single polishing module used with manual loading,
single polishing module equipped with a loading module and an unloading module enabling work to be carried out in automatic mode on a complete wafer cassette,
two or more juxtaposed polishing modules with wafer transfer between each module, performing a series type polishing process on the different stations constituting the equipment assembly. This assembly can be equipped with loading and unloading modules for loading from and unloading to the cassette so that it constitutes an automatic system.
two or more juxtaposed polishing modules with a loading system by robot linking the polishing modules to a centralised loading/unloading/transfer module. This structure enables the parts to take any type of route between the different polishing modules. Each polishing module is configured on a given elementary process, and the machine control system organises the route taken by the wafers to respect the successive polishing (and measuring, if applicable) stages defined by the user. The same elementary polishing stage can be assigned to several polishing modules to optimise the overall productivity of the machine.
The polishing modules are constructed without any mechanical parts in the polishing zone to limit any risks of pollution.